Tubing for a combustion chamber

ABSTRACT

The tubing is formed with a developed surface in which the tubes in the triangular sections are all parallel to one of the two equal sceles at an angle Alpha and all extend into the tubes of an adjacent rectangular surface via 90* bends. The tubes in the rectangular surfaces extend from the combustion chamber walls and the triangular surfaces at an angle gamma arc ctg (2 cos Alpha ) and are bent at intermediate points to extend uniformly to the lower edge of the respective rectangular surface.

United States Patent 1191 Ammann Sept. 3, 1974 [54] TUBING FOR A COMBUSTION CHAMBER 3,395,677 8/1968 Brandstetter 122/235 [75] Inventor: Heinz Ammann, Winterthur, FOREIGN PATENTS ORAPPLICATIONS swltzerland 1,163,303 9/1969 Great Britain 122 235 [73] Assignee: Sulzer Brothers Ltd., Winterthur, Switzerland Primary Examiner-Kenneth W. Sprague Attorney, Agent, or Firm-Ken on & Ken on Reill 22 Filed: Mar. 26, 1973 can & Chap, y y y 21 App]. No.: 344,582 v [57] ABSTRACT [30] Foreign Application P i it D t The tubing is formed with a developed surface in Mar 30 1972 Switzerland 4783/72 which the tubes in the triangular sections are all parallel to one of the two equal sceles at an angle a and all 52 us. or. 122/6 A 122/235 A extend the tubes Of an adjacent rectangular [51] Int. Cl. F22b 37/20 face via bends- The tubes in the rectangular [58] Field of Search 22/1316 5 6 A 235 A faces extend from the combustion chamber walls and 122/535 6 235 the triangular surfaces at an angle 'y arc ctg (2 cosa) 7 and are bent at intermediate points to extend uni- [56] References Cited formly to the lower edge of the respective rectangular UNITED STATES PATENTS surface 2,896,591 7 1959 Schroedter 122/010. 5 3 Claims, 1 Drawlng Figure TUBING FOR A COMBUSTION This invention relates to tubing for a combustion chamber, particularly, a vertical combustion chamber.

Generally, the known vertical combustion chambers have been constructed with four vertical walls to define a rectangular cross-sectional shape and a funnelshaped bottom. in some cases, the bottom has had two oppositely disposed rectangular surfaces inclined at an angle from a horizontal plane and two oppositely disposed vertically oriented isosceles triangular surfaces.

' The combustion chamber walls have been formed of tubes inclined at the same angle from the horizontal and tightly welded-together either directly or through the intermediary of bridges. These tubes have been extended into the surfaces of the funnel-shaped bottom and have been likewise tightly welded together therein.

It has already been proposed to have the tubes which extend from the combustion chamber walls into the funnel surfaces prolonged at approximately the same slope into the funnel surface. However, to do so would create a difficulty as an accumulation of tubes would occur in the region of the triangular sides. In order to overcome this difficulty the individual tubes would have to be drawn out of the funnel surfaces, or would have to be conducted around parts of the funnel surfaces, or else would have to be shifted in some unsightly manner into the arrangement of tubing. All of these solutions would, however, obstruct rational fabrication.

Accordingly, it is an object of the invention to create a simple tubing arrangement in which the transition from the rectangular surfaces into the triangular surfaces of a funnel-shaped bottom is smooth.

it is another object of the invention to provide a tubing plan in which the tubes emerging at the lower edges of the rectangular surfaces of a funnel-shaped bottom are uniformly distributed.

It is another object of the invention to provide a tubing plan from which tubing can be easily fabricated into a vertical combustion chamber having a funnel-shaped 7 bottom.

Briefly, the invention provides a tubing for a combustion chamber as above which has a plurality of tubes inclined at an angle within four surfaces for forming the four walls of the combustion chamber. in addition, the tubes extend on an angle into four other surfaces for forming the rectangular and triangular surfaces of the funnel-shaped bottom of the combustion chamber.

The tubes which extend into each triangular surface all run parallelto one of the two equal sceles wall of the triangular surface and at an angle (0:) equal to the slope angle of the rectangular surfaces. The tubes which extend into each rectangular surface, both from the wall surfaces of the combustion chamber and froman'adjacent triangular surface, are each parallel, at least initially, and all are disposed at an angle ('y) to the border between the combustion chamber walls and the rectangular surfaces. This latter angle (7) is equal to the arc cotangent of twice the cosine of the slope angle (a) of the rectangular surfaces to the horizontal. This is expressed by: I

7= arc ctg-(2 cosa).

in addition, all of the tubes within each rectangular surface of the bottom are each bent to extend toward a lower edge of the rectangular surface so that all these tubes extend to the lower, edge in a uniformly distributed'manner and in parallel to the triangular surfaces.

The relationship of the angle (7) of the tubes in the rectangular surfaces and of the angle (a) of the tubes in the triangular surfaces of the funnel-shaped bottom ensures acontinuous transition of the tubes from the triangular surfaces into the adjacent rectangular surfaces by means of simple right-angled bends. Further, the alteration of the directional path of the tubes in the rectangular surfaces need only require a single change of direction.

In accordance with a favorable further-development of the invention, the slope angle a of the rectangular surfaces satisfies the relationship S m: 1/(a/b+' 1 wherein a designates the width of the combustion chamber wall situated above the triangular surface,and

b designates the width of combustion-chamber wall situated above the rectangular'surface. By keeping to this relationship, heat stresses in the funnel surfaces are avoided to a maximum extent since the same tubing distribution results at each funnel edge at which adjacent tubes of the triangular and rectangular surfaces run parallel. The bridges between the tubes are thus of the same width, so that the abutting surfaces, when impinged by the same heat, expand equally in the direction of the tube axes.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawing-in which:

The drawing illustrates'a development of tubing according to the invention for a combustion chamber having a rectangular cross-section.

Referring to the drawing, the tubing for a combustion chamber, for example, intended primarily for heating by oil-firing, has four surfaces for forming a front wall 1, side walls 2 and 4, and rear wall 3 of a combustion chamber. These surfaces are formed of a plurality of surfaces forming the front and rear walls 1, 3 are conwalls 2, 4, respectively adjoin isosceles triangular surfaces 12, 14 respectivley at their bottom ends.

Reference will be made to the manner of construc-' tion of the tubes in one triangular surface and one rect angular surface for purposes of simplicity although it is understood that all like surfaces are formed in a like manner.

The tubes 6 in the triangular surface 12 run parallel to one side 15, that is, at an angle a relative to the horizontal line 5 while at the opposite side 16, the tubes run over a bend into the adjacent rectangular surface ll, 13 respectively. The tubes continue to run in the rectangular surface at an angle 7 relative to the horizontal line 5 to the side 20 of the rectangular surface 11. In addition, the tubes running from the front wall 1 into the rectangular surface 11 initially run into the rectangular surface at the angle 7 and are thereafter ctg 'y 2 cosa from which, as

shown above, 7 can be shown explicitely.

In accordance with the invention, the entry angle 'y 7 of the tubes into the rectangular surfaces ll, 13 is determined by the slope-angle a of the funnel. In the combustion chamber walls, the slope-angle B of the tubes is given by the number of tubes existing on the combustion-chamber perimeter, on the desired distribution of the tubes, and on the combustion-chamber perimeter. It may be advantageous to make the slope-angle a 'of the funnel slant equal to the slope-angle B of the tubes in the combustion-chamber walls, so that the tubes may run straight out of the side walls 2 and 3 into the triangular surfaces l2, 14. In general, the angle y, of the tubes running into the rectangular surfaces ll, 13 will differ from the angle B. At the boundary between the front wall I and the rectangular surface 11, the tube spacing becomes changed and, thus, the width of the bridge between the tubes. This produces a difference in the mean temperature of the adjoining surfaces.

Because walls of welded-together tubes are very flexible in a direction transverse of the tube axes, there are immaterial stresses in them. However, if two surfaces formed of welded together parallel tubes abut in a straight line parallel to the tube axes of the two surfaces, then it is possible, when the tube distribution in the one surface in markedly different from that in the other suface, for dangerous heatstresses to occur. Such a situation prevails at the funnel at the side 15 of the triangular surface 12 that abuts against the rectangle side 22.

In accordance with the invention, the tube spacing in the triangular surface 12 and in the abutting rectangular surface 13 in the half below the diagonal 21', are made equal to one another. That is, the slope-angle a of the rectangular surface, in accordance with the relationship sina l/(a/b is made dependent on the front-to-side ratio a/b of the combustion chamber.

In general, it is advantageous to make the surfaces 3, i

4, 13, 14 have tubing corresponding to that of the surfaces I, 2, l1 and 12. j

The tubes of both rectangular surfaces below the edge where the rectangular surfaces 11 and 13 abut are connected either to a common distributor, or else to individual distributors for the tubes of each rectangular surface.

What is claimed is:

l. Tubing for a vertical combustion chamber comprising four gas tight walls defining a rectangular crosssectional shape and having a plurality of interconnected tubes inclined at a first angle (B) from a horizontal plane within four surfaces defining a rectangular cross-sectional shape for forming four walls of the combustion chamber, said tubes extending from said four surfaces into four other surfaces for forming a funnelshaped bottom including two oppositely disposed gas tight rectangular surfaces inclined at a second angle (a) from a horizontal plane and two oppositely disposed gas tight verticaly oriented isosceles triangular surfaces, said tubes in each said triangular surface being disposed in parallel to one of the two equal sceles of said respective triangular surface and extending to an adjacent rectangular surface,

said tubes in each rectangular surface extending in parallel from an adjacent wall of the combustion chamber and from an adjacent triangular surface initially at a third angle (7) to the edge formed by the rectangular surface and the adjacent wall, said third angle (7) being expressed as:

y arc ctg (2 cosa) all of said tubes within said rectangular surface being bent to extend to a lower edge of said rectangular sin a= l/(a/b +1) wherein a equals the width of said wallabove one of said triangular surfaces and b equals the width of said wall above one of said rectangular surfaces. 

1. Tubing for a vertical combustion chamber comprising four gas tight walls defining a rectangular cross-sectional shape and having a plurality of interconnected tubes inclined at a first angle ( Beta ) from a horizontal plane within four surfaces defining a rectangular cross-sectional shape for forming four walls of the combustion chamber, said tubes extending from said four surfaces into four other surfaces for forming a funnelshaped bottom including two oppositely disposed gas tight rectangular surfaces inclined at a second angle ( Alpha ) from a horizontal plane and two oppositely disposed gas tight verticaly oriented isosceles triangular surfaces, said tubes in each said triangular surface being disposed in parallel to one of the two equal sceles of said respective triangular surface and extending to an adjacent rectangular surface, said tubes in each rectangular surface extending in parallel from an adjacent wall of the combustion chamber and from an adjacent triangular surface initially at a third angle ( gamma ) to the edge formed by the rectangular surface and the adjacent wall, said third angle ( gamma ) being expressed as: gamma arc ctg (2 cos Alpha ) all of said tubes within said rectangular surface being bent to extend to a lower edge of said rectangular surface in parallel to said trianguLar surfaces.
 2. Tubing as set forth in claim 1 wherein said bent tubes in each respective rectangular surface are each bent at a point located on a diagonal of said rectangular surface transversing all of said tubes in said rectangular surface.
 3. Tubing as set forth in claim 1 wherein said first angle ( Alpha ) is expressed as: sin Alpha 1/(a/b + 1) wherein a equals the width of said wall above one of said triangular surfaces and b equals the width of said wall above one of said rectangular surfaces. 